A power propulsion attachment design concept for manual wheelchairs has been developed that can successfully bridge the gap between manual and power wheelchairs for the majority of users. Manual wheelchair users benefit from the simplicity, reliability, and transportability inherent to these designs. But for all users there are situations where the strength and endurance required is unacceptable and detrimental to their health. At some point this occurs frequently enough that the user is forced to transition to a power wheelchair. While power wheelchairs can liberate the user from their physical limitations there are the disadvantages of high cost, reduced transportability, and the total loss of therapeutic physical exertion. The success of pushrim-controlled power assist devices, the latest entry into this market, have been limited by their high cost, high weight, and difficulty in installing or returning to the original manual configuration. The proposed design replaces one of the front castor assembles and with an efficient and lightweight single motor drive system steered with a manual joystick. The user can easily switch between manual and power wheelchair functionality without having the major disadvantages of either. In Phase I an existing motor, controller, and battery system will be adapted to the prototype steering system. Fundamental stability and maneuverability criteria will be evaluated. In Phase II a custom drive system will be developed and steering refined. Complete functional and user testing will then take place at an established wheelchair test facility. The proposed simple and innovative attachment allows the wheelchair user to switch easily between power and manual propulsion on any manual wheelchair. This inexpensive design allows the user themselves to choose which is appropriate for their current condition and situation they face.